Work will continue on the exploration of the physical and chemical properties of a new series of carbonic anhydrase inhibitors designed to cross the cornea in effective enough concentrations to treat glaucoma. We shall explore new substrates for carbonic anhydrase in an attempt to learn the role of the isozyme B in human red cells. Attention will be given to mitochondrial and microsomal carbonic anhydrase in kidneys; these have different properties from the cytoplasmic enzyme. We are studying the properties of the newly found carbonic anhydrase in muscle, both in cytoplasm and in particulate structure. These enzymes are strikingly different from other carbonic anhydrases, and our chemical work will form the basis for physiological experiments to reveal its role. We wish to characterize fully the red cell carbonic anhydrases of certain submammalian species, notable among fish and reptiles, to complete phylogenetic studies of this enzyme. Finally, we shall return to a problem that has vexed comparative physiologists for some 20 years -the role of carbonic anhydrase in the rectal gland of elasmobranchs.